Method for comprehensively recovering germanium and bismuth from bismuth germanate waste

Abstract

The invention discloses a method for comprehensively recovering germanium and bismuth from bismuth germanate waste, which belongs to the technical field of resource regeneration and comprises the processes of ball milling, separation of germanium and bismuth by oxidative distillation, purification of distillation waste acid, evaporation of hydrochloric acid, crystallization, recovery of crystallization raffinate and the like. According to the method, germanium and bismuth resources are fully regenerated from the bismuth germanate waste, and hydrochloric acid used in the production process is subjected to secondary recovery; the invention relates to the field of resource regeneration, and has the following beneficial effects that the direct recovery rate of germanium and the recovery rate of bismuth can finally reach 95% or above through different proportions of raw materials, and the recovery method has the advantages of high direct recovery rate of germanium and bismuth, simple process operation, low production cost, full resource utilization and the like.

Description

Technical Field

[0001] The invention relates to the technical field of resource recycling, and in particular to a method for comprehensively recovering germanium and bismuth from bismuth germanate waste. Background Art

[0002] Bismuth germanate is abbreviated as BGO, which is the general name of Bi2O3-GeO2 compounds, and often specifically refers to one of the compounds, Bi4Ge3O12. It is a cubic, colorless and transparent inorganic oxide crystal. It is insoluble in water and can emit green fluorescence with a peak wavelength of 480nm under the excitation of high-energy particles or high-energy rays (x-rays, y-rays). By recording the intensity and position of the fluorescence, the energy and position of the incident electrons, gamma rays, etc. can be calculated. This is the "eye" function of BGO, which can be used as a "detector" for high-energy particles.

[0003] With the discovery of BGO's luminescent properties, research on its scintillation properties and its application as a detection material for X-rays, gamma rays, positrons and charged particles has sprung up. Bismuth germanate crystals have the advantages of strong radiation blocking ability, high scintillation efficiency, excellent energy resolution and non-deliquescent properties. They are a new generation of scintillation crystal materials with excellent performance. They are widely used in high-energy physics, nuclear physics, space physics, nuclear medicine, geological exploration and other industrial fields. Their application scope and application volume have begun to gradually increase.

[0004] At present, the production utilization rate of BGO target materials and back-end products in industry is not high. Some BGO targets will become waste materials during production and use, resulting in waste of resources. The main components of bismuth germanate waste are bismuth germanate and other trace impurities. Germanium is a high-value rare metal and strategic, and bismuth is also an important metal resource, so the germanium and bismuth in this part of waste targets must be fully recovered and utilized. In the existing bismuth germanate waste regeneration technology, the main focus is on the recovery of germanium, and bismuth is only recovered in the form of bismuth enrichment; for example, germanium is first distilled to obtain germanium tetrachloride, and then high-purity germanium dioxide or zone melting germanium ingots and other products are produced by conventional germanium production processes; bismuth enters the distillation waste acid, and after neutralization and precipitation, bismuth concentrate is obtained, and then sent to the bismuth plant for bismuth extraction.

[0005] The significant disadvantages of the above-mentioned wet recovery process are long process flow, large amount of acid and alkali, high cost, high environmental pressure, etc. In summary, it is very important and meaningful to develop a more efficient and resource-efficient process for recovering germanium and bismuth from bismuth germanate waste based on waste minimization technology. Summary of the invention

[0006] The purpose of the present invention is to solve the above problems. The technical problem to be solved by the present invention is to provide a method for regenerating germanium and bismuth from bismuth germanate waste with high efficiency and high resource utilization rate.

[0007] The present invention comprises the following steps:

[0008] 1) Ball milling: crushing bismuth germanate waste and ball milling to obtain bismuth germanate powder;

[0009] 2) Oxidative distillation to separate germanium and bismuth: In the first stage, the bismuth germanate powder obtained in the ball milling step and concentrated hydrochloric acid are put into an enamel reactor in a certain proportion, and hydrogen peroxide is slowly added under stirring; in the second stage, hydrochloric acid is continuously added to a certain proportion, and heated and distilled to obtain crude germanium tetrachloride, which can be used to produce high-purity germanium tetrachloride, high-purity germanium dioxide and other products according to conventional processes; bismuth is retained in the distillation waste acid in the form of bismuth chloride;

[0010] 3) Purification of distillation waste acid: the distillation waste acid obtained in the step of separating germanium and bismuth by oxidation distillation is allowed to stand and cool, and then solid-liquid separation is performed to obtain a clear and transparent bismuth-containing acid solution without suspended matter;

[0011] 4) Evaporating hydrochloric acid: pumping the bismuth-containing acid solution obtained in the purification step of the distilled waste acid into an evaporator, distilling it out by negative pressure evaporation and condensing it to obtain regenerated hydrochloric acid, which can be used for surface corrosion of metals or other purposes; evaporating the residual liquid to continue to recover bismuth;

[0012] 5) Crystallization: the evaporation residue obtained in the evaporation of hydrochloric acid is placed in a crystallization tank, and after the interlayer of the crystallization tank is passed through chilled water to cool down, crystals are generated in the solution; the solid-liquid separation is carried out by suction filtration or the like, and the solid crystals obtained are hydrated bismuth chloride, which can be sold directly or sold after purification in the form of recrystallization;

[0013] 6) Recovery of crystallization residual liquid: The iron in the crystallization residual liquid is detected and analyzed. If the iron concentration in the crystallization residual liquid is lower than a certain limit, it is returned to the purification step of the distillation waste acid for reuse, and mixed with the distillation waste acid obtained in the oxidative distillation step of separating germanium and bismuth before entering the production system; if the iron concentration in the crystallization residual liquid is higher than a certain limit, soda ash, sodium carbonate or calcium hydroxide is added to adjust the pH value for a first-stage neutralization and iron removal, and after aging and solid-liquid separation, the iron slag is sent for compliant disposal, and soda ash, sodium carbonate or calcium hydroxide is added to the clear liquid to adjust the pH value for a second-stage neutralization and bismuth precipitation. After aging, the solid-liquid is separated, and the solid is a bismuth-enriched product, which can be directly sold as a bismuth raw material, and the neutralization residual liquid is sent to a sewage treatment station for compliant disposal.

[0014] The present invention increases the surface area of ​​the bismuth germanate material through the ball milling step, so as to improve the speed and efficiency of the reaction between bismuth germanate and hydrochloric acid in the subsequent step.

[0015] The invention converts a small amount of iron entrained in bismuth germanate into ferric chloride and converts part of germanium into germanium tetrachloride by adding hydrochloric acid and hydrogen peroxide in the first stage of the oxidative distillation step of separating germanium from bismuth; in the second stage, bismuth germanate and hydrochloric acid are fully reacted to generate germanium tetrachloride, and the germanium tetrachloride is volatilized and then condensed under the condition of a temperature greater than 85°C, so as to achieve full separation of germanium and bismuth, and the crude germanium tetrachloride obtained by volatilization is used to produce products such as high-purity germanium oxide by conventional processes; impurities such as iron are introduced into bismuth germanate during processing and ball milling, so the impurity iron contained in the reaction between bismuth germanate and hydrochloric acid is also converted into ferrous chloride, and the purpose of adding hydrogen peroxide is to oxidize the ferrous chloride into ferric chloride, so as to facilitate the subsequent separation of bismuth and iron.

[0016] The present invention removes suspended matter and precipitate in the spent distillation acid through the purification step of the spent distillation acid.

[0017] The present invention improves the evaporation efficiency and rate of regenerated hydrochloric acid in a negative pressure manner through the hydrochloric acid evaporation step.

[0018] The present invention reduces the solubility of bismuth trichloride by reducing the temperature of the evaporation residual liquid through the crystallization step, so that the bismuth trichloride is crystallized and precipitated after supersaturation to obtain a hydrated bismuth chloride product.

[0019] The present invention analyzes the impurity iron in the crystallization residual liquid through the recovery step of the crystallization residual liquid. If the iron concentration is low, the impurity iron in the crystallization residual liquid can be returned to the purification step of the distillation waste acid for reuse, mixed with the distillation waste acid obtained in the oxidative distillation step of separating germanium and bismuth, and then enters the production system to cyclically produce the hydrated bismuth chloride product; if the iron concentration is high, hydrolysis is required to remove the iron, and the difference in the hydrolysis pH range of trivalent iron and trivalent bismuth is used to neutralize and hydrolyze the crystallization residual liquid with alkali in two stages to first precipitate iron and then precipitate bismuth;

[0020] In summary, the present invention comprehensively recovers germanium and bismuth resources from bismuth germanate waste by "oxidative distillation separation of germanium and bismuth - evaporation regeneration of hydrochloric acid - crystallization extraction of bismuth", which has the advantages of simple germanium-bismuth recovery process, high efficiency and low cost; and complete metal recovery, with a germanium recovery rate greater than or equal to 99%; and a bismuth recovery rate greater than or equal to 95%; at the same time, the present invention has obvious cleaning characteristics, such as the hydrochloric acid used in the auxiliary material is also fully regenerated and recovered, etc., and the environmental benefits are significant.

[0021] Preferably, in the ball milling step, the bismuth germanate powder after ball milling is sieved through 80 mesh; the purpose of material particle size control is to increase the contact area between the material and hydrochloric acid and improve the reaction rate.

[0022] Preferably, in the step of separating germanium and bismuth by oxidative distillation, the input ratio (weight ratio) of bismuth germanate powder and concentrated hydrochloric acid in the first stage is 1:2-4, the molar concentration of HCl in the concentrated hydrochloric acid is greater than or equal to 9.5 mol / L, the concentration of H2O2 in hydrogen peroxide is greater than or equal to 35%, and the added amount is 1-8% of the weight of the bismuth germanate powder; the addition ratio (weight ratio) of bismuth germanate powder and concentrated hydrochloric acid in the second stage is 1:4-6, and the controlled temperature of the oxidative distillation is 100-118°C.

[0023] Preferably, in the purification step of the distillation waste acid, the distillation waste acid is cooled to room temperature and then solid-liquid separation is performed, and the obtained bismuth-containing acid liquid must be clear and transparent without suspended matter.

[0024] Preferably, in the step of evaporating hydrochloric acid, the negative pressure evaporation controls the evaporation temperature of the solution at 85-110°C, and controls the pressure in the evaporation system to be no more than 85000pa; here, the evaporation rate of hydrochloric acid is increased and the evaporation energy consumption is reduced by high temperature negative pressure. The cooling temperature of the circulating water in the condensation system is no more than 40°C, and a temperature higher than this will cause insufficient condensation of the hydrochloric acid. When the volume of the evaporated regenerated hydrochloric acid accounts for 45-70% of the volume of the bismuth-containing acid solution, stop evaporating the hydrochloric acid; if the volume of the evaporated regenerated hydrochloric acid is too small, the bismuth concentration in the evaporated residual liquid will be insufficient, resulting in a low output rate in the subsequent crystallization process; if the volume of the evaporated regenerated hydrochloric acid is too large, crystallization will occur during the evaporation process.

[0025] Preferably, in the crystallization step, the cooling circulation water temperature of the interlayer of the crystallization tank is set to 2-10°C, and the temperature of the evaporation residual liquid is kept constant at 15°C or below for 2-8 hours, and solid-liquid separation is performed by suction filtration to obtain solid crystals as hydrated bismuth chloride, which can be sold directly or sold after purification in the form of recrystallization.

[0026] Preferably, in the recovery step of the crystallization residual liquid, if the iron concentration in the crystallization residual liquid is lower than 1000ug / ml, it is returned to the purification step of the distillation waste acid for reuse, and mixed with the distillation waste acid obtained in the oxidative distillation step of separating germanium and bismuth before entering the production system to produce as much hydrated bismuth chloride as possible; if the iron concentration in the crystallization residual liquid is greater than or equal to 1000ug / ml, if it continues to be returned to the purification step of the distillation waste acid for reuse, the iron will be further enriched in the system, which will affect the purity of the product hydrated bismuth chloride, so flake caustic soda, soda ash or calcium hydroxide should be added to adjust the pH value to 2.5-3 for a first stage of neutralization and iron removal, and the aging time is 2-4 hours; after solid-liquid separation, flake caustic soda, soda ash or calcium hydroxide is added to the clear liquid to adjust the pH value to 5-7 for a second stage of neutralization and bismuth precipitation, the aging time is 2-4 hours, solid-liquid separation, the solid is a bismuth enriched product, which can be directly sold as a bismuth raw material, and the neutralization residual liquid is sent to a sewage treatment station for compliant disposal.

[0027] Beneficial Effects

[0028] A method for comprehensively recovering germanium and bismuth from bismuth germanate waste produced by the technical solution of the present invention has the following beneficial effects:

[0029] Through the recycling method in this case, through different proportions of raw materials, the direct recovery rate of germanium and the recovery rate of bismuth can eventually reach more than 95%. It has the advantages of high direct recovery rate of germanium and bismuth, simple process operation, low production cost, and full resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a schematic diagram of the steps of a method for comprehensively recovering germanium and bismuth from bismuth germanate waste.

[0031] Figure 2 The present invention provides a schematic diagram of the chemical reaction equation for the step of separating germanium and bismuth by oxidation distillation in the method for comprehensively recovering germanium and bismuth from bismuth germanate waste.

[0032] Figure 3 The present invention provides a schematic diagram of a chemical reaction equation for a recovery step of a crystallization residual liquid in a method for comprehensively recovering germanium and bismuth from bismuth germanate waste material. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below in conjunction with the accompanying drawings. Figure 1-3

[0034] Example 1

[0035] 1) Ball milling: crushing bismuth germanate waste and ball milling to obtain bismuth germanate powder; sieving the crushed and ball milled bismuth germanate powder to 80 mesh;

[0036] 2) Separation of germanium and bismuth by oxidative distillation: the bismuth germanate powder obtained in the ball milling step and concentrated hydrochloric acid are added into an enameled reactor in a weight ratio of 1:3, the molar concentration of HCl in the concentrated hydrochloric acid is 9.8 mol / L, the concentration of H2O2 in hydrogen peroxide is 50%, and the added amount is 2% of the weight of the bismuth germanate powder; the addition ratio (weight ratio) of the bismuth germanate powder and concentrated hydrochloric acid in the second stage is 1:7, and the temperature controlled by the oxidative distillation is 110-115° C.;

[0037] 3) Purification of distillation waste acid: the distillation waste acid obtained in the step of separating germanium and bismuth by oxidation distillation is allowed to stand and cool, and then solid-liquid separation is performed to obtain a clear and transparent bismuth-containing acid solution without suspended matter;

[0038] 4) Evaporating hydrochloric acid: pumping the bismuth-containing acid solution obtained in the purification step of the distilled waste acid into an evaporator, controlling the solution evaporation temperature at 95-110° C., controlling the pressure in the evaporation system to be no greater than 85000 Pa; the cooling temperature of the circulating water in the condensation system is no greater than 40° C.; stopping evaporating hydrochloric acid when the volume of the evaporated regenerated hydrochloric acid accounts for 67% of the volume of the bismuth-containing acid solution;

[0039] 5) Crystallization: the evaporation residue obtained in the evaporation of hydrochloric acid step is placed in a crystallization tank, and after the interlayer of the crystallization tank is passed through chilled water for cooling, crystals are generated in the solution; solid-liquid separation is performed by suction filtration or the like to obtain a solid crystal as the product hydrated bismuth chloride; the cooling circulation water temperature of the interlayer of the crystallization tank is set to 10° C., and the evaporation residue temperature is kept constant for 4 hours after it drops below 15° C.;

[0040] 6) Recovery of crystallization residual liquid: The iron in the crystallization residual liquid was detected and analyzed, and the iron content was 60ug / ml;

[0041] By using the method of this embodiment, the final direct recovery rate of germanium is 99.6%, and the recovery rate of bismuth is 96.7%.

[0042] Example 2

[0043] 1) Ball milling: crushing bismuth germanate waste and ball milling to obtain bismuth germanate powder; sieving the crushed and ball milled bismuth germanate powder to 80 mesh;

[0044] 2) Separation of germanium and bismuth by oxidative distillation: the bismuth germanate powder obtained in the ball milling step and concentrated hydrochloric acid are added into an enameled reactor in a weight ratio of 1:2, the molar concentration of HCl in the concentrated hydrochloric acid is 10.8 mol / L, the concentration of H2O2 in hydrogen peroxide is 30%, and the added amount is 3% of the weight of the bismuth germanate powder; the addition ratio (weight ratio) of the bismuth germanate powder and concentrated hydrochloric acid in the second stage is 1:6, and the temperature controlled by the oxidative distillation is 112-118°C;

[0045] 3) Purification of distillation waste acid: the distillation waste acid obtained in the step of separating germanium and bismuth by oxidation distillation is allowed to stand and cool, and then solid-liquid separation is performed to obtain a clear and transparent bismuth-containing acid solution without suspended matter;

[0046] 4) Evaporating hydrochloric acid: pumping the bismuth-containing acid solution obtained in the purification step of the distilled waste acid into an evaporator, controlling the solution evaporation temperature at 85-100° C., controlling the pressure in the evaporation system to be no greater than 80,000 Pa; the cooling temperature of the circulating water in the condensation system to be no greater than 40° C.; stopping evaporating hydrochloric acid when the volume of the evaporated regenerated hydrochloric acid accounts for 55% of the volume of the bismuth-containing acid solution;

[0047] 5) Crystallization: the evaporation residue obtained in the evaporation of hydrochloric acid step is placed in a crystallization tank, and after the interlayer of the crystallization tank is passed through chilled water to cool down, crystals are generated in the solution; solid-liquid separation is performed by suction filtration or the like to obtain a solid crystal as the product hydrated bismuth chloride; the cooling circulation water temperature of the interlayer of the crystallization tank is set to 2° C., and the evaporation residue temperature is kept constant for 8 hours after it drops below 15° C.;

[0048] 6) Recovery of crystallization residual liquid: The iron in the crystallization residual liquid was detected and analyzed, and the iron content was 180ug / ml;

[0049] By using the method of this embodiment, the final direct recovery rate of germanium is 99.2%, and the recovery rate of bismuth is 98.6%.

[0050] Example 3

[0051] 1) Ball milling: crushing bismuth germanate waste and ball milling to obtain bismuth germanate powder; sieving the crushed and ball milled bismuth germanate powder to 80 mesh;

[0052] 2) Separation of germanium and bismuth by oxidative distillation: the bismuth germanate powder obtained in the ball milling step and concentrated hydrochloric acid are added into an enameled reactor in a weight ratio of 1:4, the molar concentration of HCl in the concentrated hydrochloric acid is 10.2 mol / L, the concentration of H2O2 in hydrogen peroxide is 35%, and the added amount is 4% of the weight of the bismuth germanate powder; the addition ratio (weight ratio) of the bismuth germanate powder and concentrated hydrochloric acid in the second stage is 1:4, and the temperature controlled by the oxidative distillation is 105-115°C;

[0053] 3) Purification of distillation waste acid: the distillation waste acid obtained in the step of separating germanium and bismuth by oxidation distillation is allowed to stand and cool, and then solid-liquid separation is performed to obtain a clear and transparent bismuth-containing acid solution without suspended matter;

[0054] 4) Evaporating hydrochloric acid: pumping the bismuth-containing acid solution obtained in the purification step of the distilled waste acid into an evaporator, controlling the solution evaporation temperature at 95-105° C., controlling the pressure in the evaporation system to be no greater than 83000 Pa; the cooling temperature of the circulating water in the condensation system is no greater than 40° C.; stopping evaporating hydrochloric acid when the volume of the evaporated regenerated hydrochloric acid accounts for 62% of the volume of the bismuth-containing acid solution;

[0055] 5) Crystallization: the evaporation residue obtained in the evaporation of hydrochloric acid step is placed in a crystallization tank, and after the interlayer of the crystallization tank is passed through chilled water for cooling, crystals are generated in the solution; solid-liquid separation is performed by suction filtration or the like to obtain a solid crystal as the product hydrated bismuth chloride; the cooling circulation water temperature of the interlayer of the crystallization tank is set to 6° C., and the evaporation residue temperature is kept constant for 6 hours after it drops below 15° C.;

[0056] 6) Recovery of crystallization residual liquid: The iron in the crystallization residual liquid was detected and analyzed, and the iron content was 1026ug / ml. Soda flakes were added to adjust the pH value to 3 for a first-stage neutralization and iron removal, and the aging time was 4 hours; after solid-liquid separation, soda ash was added to the clear liquid to adjust the pH value to 6.5 for a second-stage neutralization and bismuth precipitation, and the aging time was 4 hours. After solid-liquid separation, the obtained solid was a bismuth enriched product, which could be directly sold as a bismuth raw material, and the neutralization residual liquid was sent to a sewage treatment station for compliant disposal;

[0057] By using the method of this embodiment, the final direct recovery rate of germanium is 99.5%, and the recovery rate of bismuth is 95.3%.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for comprehensively recovering germanium and bismuth from bismuth germanate waste, characterized in that The following steps are involved: 1) Ball milling: crushing bismuth germanate waste and ball milling to obtain bismuth germanate powder; 2) Oxidative distillation to separate germanium and bismuth: In the first stage, the bismuth germanate powder obtained by ball milling and concentrated hydrochloric acid are put into an enamel reactor in a certain proportion, and hydrogen peroxide is slowly added under stirring; in the second stage, hydrochloric acid is continuously added to a certain proportion, and heated and distilled to obtain crude germanium tetrachloride, which can be used to produce high-purity germanium tetrachloride, high-purity germanium dioxide and other products according to conventional processes; bismuth is retained in the distillation waste acid in the form of bismuth chloride; 3) Purification of distillation waste acid: the distillation waste acid obtained by the oxidative distillation separation of germanium and bismuth is allowed to stand and cool, and then solid-liquid separation is performed to obtain a clear and transparent bismuth-containing acid solution without suspended matter; 4) Evaporating hydrochloric acid: pumping the bismuth-containing acid solution obtained by purifying the distilled waste acid into an evaporator, distilling it out by negative pressure evaporation and condensing it to obtain regenerated hydrochloric acid, which can be used for surface corrosion of metals or other purposes; evaporating the residual liquid to continue to recover bismuth; 5) Crystallization: the evaporation residue obtained by evaporating the hydrochloric acid is placed in a crystallization tank, and after the interlayer of the crystallization tank is passed through chilled water to cool down, crystals are generated in the solution; the solid-liquid separation is carried out by suction filtration or the like, and the solid crystals obtained are hydrated bismuth chloride, which can be sold directly or sold after purification in the form of recrystallization; 6) Recovery of crystallization residual liquid: The iron in the crystallization residual liquid is detected and analyzed. If the iron concentration in the crystallization residual liquid is lower than a certain limit, it is returned to the purification step of the distillation waste acid for reuse, and mixed with the distillation waste acid obtained from the oxidative distillation separation of germanium and bismuth before entering the production system; if the iron concentration in the crystallization residual liquid is higher than a certain limit, soda ash, sodium carbonate or calcium hydroxide is added to adjust the pH value for a first-stage neutralization and iron removal, and after aging and solid-liquid separation, the iron slag is sent for compliant disposal, and soda ash, sodium carbonate or calcium hydroxide is added to the clear liquid to adjust the pH value for a second-stage neutralization and bismuth precipitation. After aging, the solid-liquid is separated, and the solid is a bismuth-enriched product, which can be directly sold as a bismuth raw material, and the neutralization residual liquid is sent to a sewage treatment station for compliant disposal.

2. A method for comprehensively recovering germanium and bismuth from bismuth germanate waste according to claim 1, characterized in that In the ball milling step, the bismuth germanate powder after ball milling is sieved through 80 mesh.

3. A method for comprehensively recovering germanium and bismuth from bismuth germanate waste according to claim 1, characterized in that In the step of separating germanium and bismuth by oxidative distillation, the input ratio (weight ratio) of bismuth germanate powder and concentrated hydrochloric acid in the first stage is 1:2-4, the molar concentration of HCl in the concentrated hydrochloric acid is greater than or equal to 9.5 mol / L, the concentration of H2O2 in hydrogen peroxide is greater than or equal to 30%, and the added amount is 1-8% of the weight of the bismuth germanate powder; the addition ratio (weight ratio) of bismuth germanate powder and concentrated hydrochloric acid in the second stage is 1:4-6, and the temperature controlled by the oxidative distillation is 100-118°C.

4. A method for comprehensively recovering germanium and bismuth from bismuth germanate waste according to claim 1, characterized in that In the purification of the distillation waste acid, the distillation waste acid is cooled to room temperature and then solid-liquid separation is performed, and the obtained bismuth-containing acid liquid must be clear and transparent without suspended matter.

5. A method for comprehensively recovering germanium and bismuth from bismuth germanate waste according to claim 1, characterized in that In the evaporation of hydrochloric acid, the negative pressure evaporation controls the evaporation temperature of the solution to be between 85°C and 110°C, controls the pressure in the evaporation system to be no greater than 85000 Pa, and controls the cooling temperature of the circulating water in the condensation system to be no greater than 40°C. When the volume of the evaporated regenerated hydrochloric acid accounts for 45% to 70% of the volume of the bismuth-containing acid solution, the evaporation of hydrochloric acid is stopped.

6. A method for comprehensively recovering germanium and bismuth from bismuth germanate waste according to claim 1, characterized in that In the crystallization step, the cooling circulating water temperature of the interlayer of the crystallization tank is set at 2-10°C, and the temperature of the evaporation residual liquid is kept constant for 2-8 hours after it drops to below 15°C, and solid-liquid separation is performed by suction filtration to obtain solid crystals as hydrated bismuth chloride, which can be sold directly or sold after purification in the form of recrystallization.

7. A method for comprehensively recovering germanium and bismuth from bismuth germanate waste according to claim 1, characterized in that In the recovery step of the crystallization residual liquid, if the iron concentration in the crystallization residual liquid is lower than 1000ug / ml, the crystallization residual liquid is returned to the purification step of the distillation waste acid for reuse, and is mixed with the distillation waste acid obtained in the oxidative distillation step of separating germanium and bismuth before entering the production system; if the iron concentration in the crystallization residual liquid is greater than or equal to 1000ug / ml, then flake caustic soda, soda ash or calcium hydroxide is added to adjust the pH value to 2.5-3 for a first-stage neutralization and iron removal, and the aging time is 2-4 hours; after solid-liquid separation, flake caustic soda, soda ash or calcium hydroxide is added to the clear liquid to adjust the pH value to 5-7 for a second-stage neutralization and bismuth precipitation, and the aging time is 2-4 hours. After solid-liquid separation, the solid is a bismuth enriched product, which can be directly sold as a bismuth raw material, and the neutralization residual liquid is sent to a sewage treatment station for compliant disposal.

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